1. Field of the Invention
The present invention relates to a channel quality determining circuit and related method thereof, and more particularly, to a circuit that determines a channel quality of a signal transmitting channel according to a header of a packet and related method thereof.
2. Description of the Prior Art
General local area network (LAN) systems include a specific signal transmitting frequency band. Since some of the frequency bands are free for use, overlapped bands may be utilized by some different LAN systems for transmitting signals. For example, center frequencies of the signal transmitting frequency bands in Bluetooth (BT) system and wireless local area network (WLAN) system are substantially at 2.4 GHz. Thus, if the BT system and the WLAN system are working simultaneously, the transmitted signals may probably interfere with each other. More specifically, since a working bandwidth of a channel in the BT system is 1 MHz and there are 79 channels ranging from 2402 MHz to 2480 MHz, while the operational frequency band of the WLAN system is within a range from 2412 MHz to 2484 MHz, the channels utilized by the two communication protocols described above are substantially overlapped. In a case where the WLAN system is currently working, if the BT system also wants to transmit data via a working frequency band overlapped with the working frequency band of the WLAN system, the signal transmission quality of the WLAN system is affected. Similarly, the working WLAN system also has a severe interfere to the BT system. Thus, how to enable a plurality of different wireless transmitting systems whose operational frequency bands are overlapped with each other to quickly determine an available channel to avoid using an interfered channel is an issue to be solved in the pertinent field.